Notes on the Accusys ACS 7500/75130 RAID box
7500 is a very nice IDE
Unlike more common IDE mirroring (RAID1) solutions, this is a real
hardware RAID system, taking two conventional IDE drives and making them
appear as a single IDE drive to software.
This means the ACS 7500 is completely invisible to software.
In fact, the system comes with NO software at all -- no drivers,
nothing (actually, this has changed recently -- the things no longer
come with a printed manual (boo) but now include software that can
"manage" (or more accurately, monitor) the array).
None are needed.
Most operating systems and computers that can support standard IDE drives
can use this box.
In fact, if you simply apply power to the box, it is capable of
being used as a stand-alone disk duplication system, no computer
or operating system required.
Design and Operation Notes
- The box is made of moderately well built aluminum with plastic slide
The case takes up two adjoining half-height bays in the front of your
The bays must be immediately adjoining, some name brand cases put a gap
between the two front-mounted 5.25" devices, rendering this device
unusable (or at least, your case may need some modification).
The case has notches which will permit installation in many boxes which
have "fingers" on which each half-height device will sit.
Many cases have an overhanging lip which will prevent the drive trays
from being removed from the front of the machine with all the plastic
You need to decide how important this is to you.
- Two keys are used to "lock" in the drives.
Both locks on one ACS7500 use either key (two are included) and all
Accusys boxes examined so far use the same key.
In fact, the locks are more a mechanical mount, the security of the
lock is almost non-existent, as there are no tumblers in the locks.
I'm of mixed feelings on this -- I don't like appearances of security
when none really exists, but then, real locks would probably cause far
more problems then they would solve.
- A number of LEDs give a very good status report on both the
drives and the RAID array.
LEDs are provided to indicate power to each drive, activity on each
drive, redundant indication of the health of each drive, and a bar graph
indicating how far along the mirroring is progressing.
When the drive is in its standard operating mode, the remirror
status bar graph becomes a scanning light, letting you know that it is
alive and functioning.
I'm very impressed by the light show this thing puts on -- in some ways
it may be excessive, but I'll tell ya, the thing lets you know how
it is doing.
If the array is degraded in some way, you will know it in no uncertain
- The ACS7500 has a beeper which will help draw attention to it
if it has a failed drive.
The beeper is loud enough to be heard, but not very annoying, which may
or may not be good (the ArcoIDE products have a beeper so loud, they put
a "silence" switch on them).
The Accusys box can be silenced simply by unlocking the failed drive.
Apparently, if you have one drive unlocked, it assumes you know you are
running in a degraded mode, and thus, no reason to be vocal about it.
- There is one large fan that pulls air across the drives.
I am very pleased with the temperature it keeps the drives --
a pair of 80G drives were kept at "barely warm" (by finger)
The fan does make noise, but not unreasonable amounts for any system
which is likely to have multiple drives in it.
The tone of the fan is not unpleasant to me.
(however, in the move to "quiet PCs", this may be much louder
than the rest of the system. I have heard one complaint from a
home user who added it to their home system).
- Early ACS7500 boxes had no provision for the new "Big Drives"
extension to the IDE standard, the standard used on newer, larger
than 137G IDE drives.
The most recent box a client of mine bought had a note stuck in it
which says, "ACS-7500 now supports Big Drive (ATA-6) and you can install
any hard drives with capacities over 137G ...".
There is, unfortunately, no upgrade for the old ACS7500 boxes.
Accusys's web site does indicate how to recognize which ACS7500 boxes
are "Big Drive" compatable, it is not obvious from the box itself,
although later ones have the model number ACS75130 instead.
- The ACS7500 can be used to duplicate a disk, and potentially, could
be used to "upgrade" a disk pair.
This is done by removing one of the drives in an existing pair,
mirroring the remaining drive against a bigger drive, and then removing
the remaining smaller drive and replacing it with another larger drive,
and remirroring (again).
At this point, the ACS7500 will report a "larger" drive size to your
system on the next reboot.
What you can do with this system depends upon your OS.
If you have a semi-intelegent OS (i.e., OpenBSD), you can alter the
partition table and disk label and add new partitions.
Other OSs (Windows) may be able to have existing partitions "expanded"
using a program like Partition Magic.
It is important to understand, however, that being an OS ignorant device,
the ACS7500 isn't going to do a thing to help you expand your OS into
the new disk space, you are going to have to figure that out on your own.
- Compaq users may have some issues.
I have found that some Compaq systems have very weird drive translation
geometries, and (related?) the ACS7500 will not properly establish a
mirror if attached to the Compaq computer at power-up.
A workaround for this is the following:
- Unplug the ACS7500 from the IDE cable, apply only power to it.
- Establish the mirror (i.e., "lock down" the second drive).
the box should start mirroring now.
- Power down the box (no need to wait for the mirroring to complete)
- Plug in IDE cable, power box back up, remirroring will resume.
- When remirroring, the ACS7500 will blink at a rate that roughly
tells you how it is doing with remirroring.
If you find it not blinking, you have an unhappy ACS7500, see the Compaq
Odds are, it probably *is* blinking, just very, very slowly, one
was seen to be blinking at roughly a half-hour on, half-hour off, and
then it gave up the mirroring.
If the machine is busy using the hard disk while the mirroring is taking
place, I have noted the blinking slowing.
- It *may* be wise to disable write-back caches on the drives before
using them in the ACS7500, though Accusys makes no statement about this.
I know people who consider it a requirement to disable write-back caches
on disks in general.
Not a bad idea, though at a significant performance penalty.
- Rebuilding a mirror takes time -- a 20G drive takes around an hour
and a half, an 80G drive takes around six hours.
System is operational at this time, performance is somewhat degraded,
but not horribly.
Buying a 160G drive when you need a 30G drive "just because it was only
$20 more" isn't a good economy when mirroring drives, the remirror
time will make you regret over-sized systems.
- Netware 3/4 notes: The Accusys 7500 box and Netware's IDE drivers
are very unhappy with each other.
Performance while remirroring is basicly ZERO, and in fact, if
anything attempts to write to or read from the disk, the server will
tie itself up in knots until it ABENDs.
I have no idea what is going on here, a wild speculation is that the
IDE driver is querying the "drive" and the drive is continually saying,
"yes, I'm not idle".
It just acts like Netware doesn't want to disturb the drive.
DO NOT USE THE ACCUSYS BOX DIRECTLY WITH THE NOVELL IDE DISK DRIVERS.
Netware can not be running while the system is remirroring.
Once the mirror is complete, however, it WILL run just fine, but that
very much defeats the purpose of this box.
Fortunately, there is a very simple solution: use a third-party IDE
driver. I have found the Promise UltraDMA cards have their own Netware
driver which instantly and completely resolves this problem, and for
about $50, it makes the Accusys 7500 an ideal partner for a Netware
I found the Promise driver very easy to work with, though being a .HAM
driver, it does require your Netware 3 server be fully patched.
You can retrofit the Promise driver onto a drive set that was created
- I have received a report that at least some motherboards have trouble
with these devices.
Other than the above mentioned Compaq systems, I don't have much more
hard info on this, but I'll be keeping my eyes open for more info
and experiences on this.
- Accusys actually DOES have a "support" section on their website,
Not sure if I never noticed it before, or if it is new. User interface
is kinda strange, but there are a lot of odd bits of info there.
- At least the new 75130 boxes can be monitored through software,
either through the ATA interface, or via a three-pin serial jack
hiding on the back of the drive (over the master/slave jumper).
Looking for more details on this. I'll report if I get them.
As of October, 2005 (probably earlier), Accusys was shipping
"management" and monitoring software with most of their products.
While the information conveyed by this program is potentially
useful (such as monitoring a machine in a remote office or data
center), the application leaves a lot to be desired.
Installed as intended for local monitoring, it requires the
installation of a web server, Java and the use of a web browser.
Sorry, based on the history of Microsoft's web server, I refuse
to load it on a machine it does not need to be loaded on.
Further, my success with the SATA devices has been very poor -- the
Accusys software could not detect an IDE interface to talk to the drive,
my guess is that is due to hardware specific SATA drivers obscuring the
interface to the application.
However, they may also be aware of this problem.
Curiously, the SATA versions of this application include the serial
Unfortunately, the machines I really wanted to put this in had other
needs for their only serial port, so this also proved to be a problem.
I have some reason to believe it may be possible to monitor this
device in other ways, other than the web browser and webserver.
Getting the Accusys products
The simple Accusys IDE/SATA products are no longer avaialble new, as
far as I am aware, having been out of production since 2010 or earlier.
Used products are out there. Buyer beware, of course.
Holland Consulting home
Contact Holland Consulting
since April 6, 2004
(C)opyright 2004, Nick Holland, Holland Consulting
$Id: acs7500.html,v 1.10 2005/12/09 00:02:24 nick Exp $